Actuator device

ABSTRACT

The present invention relates to a device which can be employed in connection with oil and/or gas wells for the purpose of increasing the well&#39;s production. The device comprises an external structure, in which external structure a first and a second pressure-influenced bellows device is mounted, where the first and second pressure-influenced bellows devices are in fluid connection with each other via a support device. At the end opposite the connection with the support device, the second pressure-influenced bellows device is connected to a movable sleeve. The device further comprises a pivotable or rotatable closing mechanism for the device, where the closing mechanism is connected to the movable sleeve.

The present invention relates to a device for use in connection with oil and/or gas wells onshore or offshore.

In connection with various types of work and operations carried out during drilling, completion, start-up and operation of an oil and/or gas well onshore or offshore, equipment and tools are employed which are controlled or operated electrically, hydraulically, by means of pressure, etc.

A plurality of units in a well, for example valves such as gas lift valves, are controlled by the pressure to which they are exposed, and are therefore designed to be opened or closed within specific pressure ranges. However, if a sudden rise or drop in pressure occurs in the well, these gas lift valves could be opened or closed inadvertently on account of their predetermined range of operation. As a result, undesirable and dangerous situations could arise. Equipment and tools in a well could be inadvertently activated/deactivated, thereby causing undesirable and potentially dangerous situations to arise.

An object of the present invention is to provide a device which can be activated or deactivated in a safe and controlled manner by pressure differences in a fluid in a well.

This object is achieved by a device as indicated in the following independent claim, where further features of the invention will become evident from the dependent claims and the description below.

It should be understood, however, that the device according to the present invention may also have other areas of application than down in a well, for example in connection with processing equipment which may be located on the seabed or also topsides or on shore.

According to the invention a device is provided, particularly suitable for use in an oil and/or gas well. The device comprises an external structure and a pressure-influenced bellows, where this bellows comprises a first and second bellows device in fluid communication with each other, where the first and second bellows devices are arranged relatively to the external structure in such a manner that during use they can experience different pressure influence. This may be adapted in several ways, where the one bellows device is located in a space which is separated from the space in which the other bellows device is located, thereby enabling them to be influenced pressure-wise by different external fluids. That the bellows devices are in fluid communication means that a change in pressure influence on one bellows device is transmitted to the other bellows device via the fluid communications.

According to the invention the external structure comprises a through-going bore and the pressure-influenced bellows is mounted at least partly in an annulus arranged round the through-going bore. The annulus is at least partly composed of the external structure. One of the bellows devices is connected to a device for activation of a unit. By this one obtains that a large area of a bellows is subjected to a pressure change and thereby obtain a more reliable activation of pressure-activated units in a well.

According to an aspect of the invention, the unit to which the bellows is connected may be a valve device. This valve device may be mounted in the through-going bore in the external structure for opening and closing the through-going bore. The connection between the bellows and the valve device may be arranged so as to enable the valve device to be activated between an open and a closed position on movement of the bellows as a consequence of pressure influence on the bellows. In a possible embodiment there may also be locking devices which are released, thereby releasing for example a valve device from a first position to an operational position where the valve device as such can now be controlled by pressure variations in the ambient fluid. By allowing the device according to the invention to be able to be operated at a high pressure, whereby it opens a valve device in the through-going bore, it can act as a locking device for a second pressure-activated valve device. This second pressure-activated valve device is thereby prevented from being activated before the device according to the invention is activated, whereby a more reliable activation of pressure-activated units in the well is achieved.

According to another aspect the bellows devices may be arranged relatively outside the through-going bore in the external structure. This means that the through-going bore can be designed without constrictions as a result of the bellows device. The through-going bore can therefore have the desired diameter, either fixed or varying, through the device. This can be achieved by the annulus in which the bellows is mounted being, for example, arranged internally in the external structure. This annulus may have at least one opening or a plurality of openings to the through-going bore round the circumference of the through-going opening. Alternatively, the bellows devices may be mounted at least partly internally in the through-going bore in the external structure. In a variant there may be a recess in the wall of the through-going bore and a sleeve element provided internally in the bore, thereby forming an annulus between them. Alternatively, a sleeve may be provided internally in the bore in the external structure, at a distance therefrom, so that the annulus is formed between these, where the annulus is closed at one end, where the sleeve, the structure and the bellows are configured in such a manner that one of the bellows devices is mounted in a closed space formed inside this annulus and is therefore not influenced by the fluid located in the through-going opening. The sleeve is connected in a suitable fashion to the external structure, for example by welding, threaded connection or the like.

According to an aspect of the invention, both the first and second bellows device may be arranged in the annulus formed between the sleeve and the external structure. Alternatively, one of the bellows devices may be arranged in the annulus formed round the through-going bore, while the other bellows device is arranged at the side of this annulus.

According to an aspect of the invention, at least one of the bellows devices of the bellows may be formed with an annular structure. In a variant at least one of the bellows devices may then form a closed ring and in another variant this ring may not be completely closed. This annular structure is thus complementary to the annulus. Alternatively, both the bellows devices may have an annular structure and be mounted in the annulus. The annulus will then be divided into two separate chambers with one bellows device in one chamber and the other bellows device in the other chamber. In such an embodiment at least one of the chambers may be open to the through-going bore.

In an alternative embodiment of the present invention, the first and second pressure-influenced bellows devices may cover only a part of the circumference of the annulus. The first and second pressure-influenced bellows devices may be composed of a number of separate, isolated bellows devices, where these are arranged at a distance from one another round the circumference of the annulus. For example, four separate, isolated pressure-influenced bellows devices may be mounted in the annulus, where these are arranged in twos diametrically above one another. In yet another alternative embodiment of the present invention one pressure-influenced bellows device may be designed to extend round the whole circumference of the annulus, while the other pressure-influenced bellows device may be composed of a number of separate, isolated bellows devices.

Depending on the configuration of the external structure and the annulus, the arrangement of the first and second pressure-influenced bellows devices in the annulus may cause one or both of the first and/or second pressure-influenced bellows devices to be subjected to the influence of a fluid located in the through-going bore in the external structure. In an alternative embodiment one pressure-influenced bellows device may in addition also be influenced by an activation device, or only by an activation device where the activation device may be controlled electrically, mechanically, electromagnetically, etc.

When viewed in a section in its longitudinal direction which in this case is substantially parallel to the through-going bore, such a pressure-influenced bellows device may have a shape which may be oval, polygonal, curved, but preferably not circular, with the result that compression or extension of the bellows device may easily be achieved. A compression or an extension of a pressure-influenced bellows device is obtained by the bellows device being subjected to an external influence, where this external influence may, for example, be a pressure, a mechanical influence or the like. According to an embodiment of the present invention the pressure-influenced bellows devices are made of a number of sections or disks, which are assembled to form the pressure-influenced bellows device. The different sections or disks will then be glued, welded or joined together in another suitable way. The pressure-influenced bellows devices may also be envisaged manufactured by machining, casting etc. The pressure-influenced bellows devices are preferably made of a metallic material, but they may also be made of a non-metallic material or an elastomeric material. It is also possible for a pressure-influenced bellows device to be made of several different materials.

According to an aspect of the invention, the first and second bellows devices may be in fluid connection with each other via a support device, said support device forming a transverse wall in the annulus. Transverse wall in this context should be understood to refer to a wall which extends in a radial direction, forming a ring surface. Furthermore, this transverse wall will also divide the annulus into two annular chambers. The two annular chambers are then arranged behind each other along an axis of the through-going bore. The support device is connected in a suitable fashion to the inside of the external structure's through-going bore and the outside of the sleeve where a sleeve is provided internally in the through-going bore.

According to an aspect, the first and second pressure-influenced bellows devices and the support device may be filled with an incompressible fluid. As the pressure-influenced bellows devices shall contain a fluid, preferably an incompressible fluid, they will either be closed at their ends or be designed so that they can be connected to the support device, thereby forming a closed volume internally in the unit composed of the pressure-influenced bellows devices and the support device. How this connection is carried out and the design of the support device will be explained later.

Furthermore, the first and second pressure-influenced bellows devices may be designed with substantially the same shape and volume. Alternatively, the first and second pressure-influenced bellows devices may be designed with substantially the same shape, but with different volume. In yet another alternative the first and second pressure-influenced bellows devices may be designed with different shape and volume. When one bellows device is influenced by pressure and compressed, a volume of fluid will be displaced from this bellows device over to the other bellows device which will be extended in order to make room for the volume displaced from the first bellows device. The length of the compression and/or extension depends on the shape and volume of the respective bellows devices. The bellows devices may be arranged to have corresponding lengths or there may be ratios between the bellows devices and compression/extension.

In an embodiment the present invention may be regarded as a pressure-controlled actuator, where the pressure-controlled actuator comprises an external structure and a pressure-influenced bellows.

The external structure is provided with a through-going bore, where the bellows are mounted in an annulus in connection with the through-going bore.

As the device or the pressure-controlled actuator should be capable of being connected to equipment and/or tools, one or both ends of the actuator's external structure may be designed to be able to be connected or coupled in a fluid-tight manner to the said equipment and/or tools. The external structure's end(s) (external circumference) may then be provided with a threaded portion, a flange for a bolt or screw connection, include rapid couplings etc., thereby enabling the pressure-controlled actuator to be connected via one end, for example to a gas lift valve mounted in a production tubing, and with a pressure pipe connected to one of the bellows devices, where the pressure pipe is used for activating/deactivating the pressure-controlled actuator. The pressure-controlled actuator's external structure may be manufactured in a single piece, or it may be composed of several component elements, which together form the external structure.

In an embodiment of the present invention, when it is mounted in the external structure, the first pressure-influenced bellows device may only be supported by the support device, while the second pressure-influenced bellows device will be supported by the support device at one end and at the opposite end by a sleeve which is axially movable in the external structure.

In one embodiment, the annulus may have an axial length and a radial dimension (width), where the bellows which are mounted in this annulus will have a width which is less than the “width” of the annulus, when viewed in the same direction as the through-going bore. This means that when they are influenced, the first and second pressure-influenced bellows devices can move “freely” in the axial direction of the external structure, thereby permitting them to be extended/compressed in their axial directions. The bellows device is furthermore configured in such a manner that all volume change takes place on extension/compression in the axial direction. The first and second pressure-influenced bellows devices are furthermore “hydraulically” connected to each other via the support device, with the result that the pressure-influenced bellows devices will mutually influence each other in their axial direction. If, for example, the first pressure-influenced bellows device is influenced so that it is compressed, the compression will be “transmitted” via the support device, with the result that the second pressure-influenced bellows device is extended by a certain length.

In a similar manner an influence on the second pressure-influenced bellows device will cause the first pressure-influenced device to be extended or compressed, depending on whether the second pressure-influenced bellows device was compressed or extended. The incompressible fluid will then be “transmitted” from one pressure-influenced bellows device to the other, whereby in an embodiment it will be possible to control and monitor the opening and closing of the pressure-controlled actuator by means of this “transmission” of fluid between the pressure-influenced bellows devices.

In an embodiment of the invention the support device is securely connected in a suitable manner to the walls of the annulus. This may be implemented, for example, by welding, gluing, screwing etc. Since the support device has a radial dimension (width) which substantially corresponds to the width of the annulus, the support device and walls of the annulus including an end wall of the annulus will form a fluid-tight space, in which fluid-tight space one of the pressure-influenced bellows devices is mounted. In an alternative embodiment, therefore, this fluid-tight space may be influenced by a pressure fluid controlled from a remote location, or a pressure set when the device was assembled. In this fluid-tight space, however, an elastic element surrounding the first pressure-influenced bellows device may also be mounted, for example a nitrogen package, one or more springs etc., where these will be capable of creating a “pre-tensioning” or bias against the pressure-influenced bellows device.

According to an embodiment of the invention the support device is in the form of a hollow, closed cylinder, where a through-going hole or opening is provided in the closed cylinder's top and bottom surface, when viewed in the cylinder's longitudinal direction. The first and second pressure-influenced bellows devices are then connected via their open end with the holes in the support device's top and bottom surface, with the result that the first and second pressure-influenced bellows devices together with the support device form a closed, fluid-tight unit. It should be understood, however, that the support device may also have other shapes.

According to an embodiment of the present invention a “floating” piston may be provided internally in the support device, where the piston is permitted to be moved in the support device's axial direction when one or both of the pressure-influenced bellows devices are subjected to an external influence. The piston has a radial dimension (diameter) which is substantially the same radial dimension as the support device's internal surface (circumference). When the piston comes into contact with the support device's top or bottom surface, the piston will not move further, thereby causing the movement of the pressure-influenced bellows devices to also be stopped.

In another embodiment of the present invention a delay device may be provided in the support device, where this delay device is intended to delay the flow of the incompressible fluid through the support device. In its simplest form this delay device may comprise a plate provided with one or more through-going holes. The plate is attached internally in the support device in a suitable fashion.

Since the object of the present invention is to provide a device which operates within a predefined pressure range, the pressure-influenced bellows devices may be mounted in the annulus in such a manner that the support device in itself forms a delimitation (end stop) for the movement the first and the second pressure-influenced bellows devices respectively are permitted to perform. This means that if the first pressure-influenced bellows device is subjected to a pressure which causes the first pressure-influenced bellows device to be compressed in its axial direction, the support device, which acts as an end stop, will prevent a further extension of the second pressure-influenced bellows device from occurring. Correspondingly, when the pressure round it is increased, the second pressure-influenced bellows device will be permitted only a certain amount of travel in its axial direction before the second pressure-influenced bellows device's movement is stopped by the support device, whereby the first pressure-influenced bellows device is also prevented from being further extended.

In an alternative embodiment an end stop may be composed of a sleeve which is preferably provided on the inside of the support device, in which case the sleeve will extend through the through-going hole in the support device's top and/or bottom surface and continue for a length into the pressure-influenced bellows device's axial direction. Such an end stop, in the form of a sleeve, may then be provided on each side of the support device, or only on one side.

It should also be understood that the sleeve forming the end stop may be arranged externally of the pressure-influenced bellows device or devices. In this case the sleeve will be connected in a suitable manner with the support device's top and/or bottom surface. The pressure-influenced bellows devices may then be provided with a radially extending flange at the end opposite the support device, where the flange is brought into abutment with the sleeve when the pressure-influenced bellows device is compressed by a certain length. A further compression of the pressure-influenced bellows device will therefore not be possible.

The end stop may also be composed of a flange or the like mounted in the actual annulus.

With regard to the above it should be noted that the travel permitted for the first and/or second pressure-influenced bellows device will be dependent on a number of parameters, for example the well conditions, the type of work and/or operation that has to be conducted, size of the tubing etc., where a person skilled in the art will know how this should be done.

In an embodiment of the present invention one or both of the pressure-influenced bellows devices may be designed so that when a desired compression of the pressure-influenced bellows device is achieved, the pressure-influenced bellows device will be substantially compressed, with the result that a further compression of the pressure-influenced bellows device cannot be achieved. This means that in its maximum compressed position, the pressure-influenced bellows device will behave like a solid, compact element, thereby giving the pressure-influenced bellows device great mechanical strength and pressure resistance.

Due to the fact that the fluid-tight space in which the first pressure-influenced bellows device is located is supplied with a fluid and subsequently pressurised at a specific pressure, where this causes the first pressure-influenced bellows device to be subjected to a preset pressure, the first pressure-influenced bellows device will be influenced by this preset pressure and compressed against the support device. The first pressure-influenced bellows device will then be able to be completely compressed, i.e. it assumes the position of a solid, compact element, which cannot be further compressed. This compression of the first pressure-influenced bellows device will then cause the second pressure-influenced bellows device to be extended for a length, with the result that the second pressure-influenced bellows device, which in an embodiment is connected to the movable sleeve, will permit a damper to rotate out to abut with one or more “seats” in the external structure's bore, thereby causing the damper to shut off the longitudinal bore in the external structure. Where the second pressure-influenced bellows device is connected to a flap, the flap will be pushed out of the stationary sleeve, whereby, on account of its properties, the flap will be bent or curved in order thereby to close the longitudinal bore in the external structure.

The transmission of the axial movement between the first and the second pressure-influenced bellows device, however, may also be carried out in other ways than the first pressure-influenced bellows device being subjected to a fluid pressure, for example by means of a transmission mechanism. The transmission mechanism may, for example, be a slide valve, a rack transmission or the like which is attached internally in the external structure's bore and connected in a suitable manner to the first pressure-influenced bellows device. By influencing the transmission mechanism, this influence will be transmitted to the first pressure-influenced bellows device. The transmission mechanism may furthermore be capable of being influenced hydraulically, electro-hydraulically, electrically, electromagnetically, magnetically etc.

In an embodiment of the present invention the first and/or the second pressure-influenced bellows device may be designed to be capable of being filled with or drained of the fluid it contains, thereby enabling the pressure and/or the fluid it contains to be varied/replaced.

Other advantages and special features of the present invention will become clear from the following detailed description, the attached figures and the following claims.

The invention will now be described in greater detail with reference to the following figures, in which:

FIG. 1 illustrates a first embodiment of a device according to the present invention,

FIG. 2 illustrates a second embodiment of a device according to the present invention, and

FIG. 3 illustrates a third embodiment of a device according to the present invention.

FIG. 1 illustrates an embodiment of a device according to the present invention, where the device comprises an external structure 1, such as the cylindrical wall of a pipe or similar. In the illustrated embodiment, the external structure 1 is designed in a single piece. It may also be envisaged, however, that the external structure 1 is composed of several elements, which when assembled form the external structure 1.

The external structure 1 is provided with a through-going bore 2, with the result that the external structure 1 is open at its ends. Internally in the through-going bore 2 there is further provided a sleeve 3, said sleeve 3, which is stationary, having an external diameter which is less than the through-going bore's 2 internal diameter. This will result in the formation of an annulus between the wall of the external structure 1 and the stationary sleeve 3. The stationary sleeve 3 is attached in a suitable manner to the external structure 1, internally therein. Furthermore, the annulus which is delimited by the through-going bore 2 in the external structure 1 and the stationary sleeve's 3 external diameter will be closed at one end of the external structure 1/the stationary sleeve 3 by a plate 4. At its opposite end the external structure 1/the stationary sleeve 3 will be open.

Internally in the annulus which is delimited by the through-going bore 2 and the stationary sleeve 3, a support device 5 is provided, which support device 5 is securely connected to the external structure 1 and the stationary sleeve 3. Two pressure-influenced bellows devices, the first pressure-influenced bellows device 6 and the second pressure-influenced bellows device 7 are furthermore connected to the support device 5.

The first and second pressure-influenced bellows devices 6, 7 are provided as a bellows, having a shape resembling an accordion bellows, where a plurality of sections or disks 8 are assembled to form the actual bellows. This may be implemented, for example, by welding, gluing or by interconnecting the sections or disks 8 in another suitable manner.

The two pressure-influenced bellows devices 6, 7 are interconnected via the support device 5. The outermost section or disk 8 (i.e. an end section) in one end of the pressure-influenced bellows device 6, 7 is then welded, glued or connected in another suitable manner to each side of the support device 5. The pressure-influenced bellows devices 6, 7 are closed at their other end. For its part the support device 5 is connected with the inside of the bore 2 and the sleeve's 3 outer surface. This may be implemented, for example, by welding, gluing, screwing or in another suitable fashion.

The design of the actual support device 5 will be explained later.

In a similar manner to the first pressure-influenced bellows device 6, the second pressure-influenced bellows device 7 is closed at its other end (i.e. the end which is opposite the connection with the support device 5) and in addition connected to a flap mechanism 9 unit.

Since the support device 5 is securely connected to the inside of the through-going bore 2 and the outer surface of the stationary sleeve 3, the support device 5 will form a fluid-tight partition internally in the external structure between the first and second pressure-influenced bellows devices 6, 7. This results in the formation of a closed space 10, which closed space 10 encloses the first pressure-influenced bellows device 6. This closed space 10 is filled with a fluid, for example nitrogen under pressure, with the result that the first pressure-influenced bellows device 6 is subjected to a desired “pre-tensioning” or bias. Depending on its magnitude, this pre-tensioning will influence the first pressure-influenced bellows device 6, causing it to be compressed. The closed space 10 is filled by arranging a through-going hole (not shown) in the external structure 1, to which hole a non-return valve for example is attached.

It may, however, also be conceivable that the first pressure-influenced bellows device 6 may be influenced by an activation mechanism 11, with the result that the closed space 10 does not have to have a preset pressure. In this case the activation mechanism 11 may be designed so as to transmit or apply a force to the first pressure-influenced device 6, causing it to be compressed or extended in its axial direction. The activation mechanism 11 may, for example, be designed so as to be activated electrically, hydraulically, magnetically, electromagnetically etc.

In a similar manner a space 12 will also be formed round the second pressure-influenced bellows device 7, which space 12 is formed by the support device 5, the through-going bore 1 in the external structure 1 and the stationary sleeve 3. The space 12 will be open at the end opposite the support device 5. The second pressure-influenced bellows device 7 will then also be subjected to an external influence, for example from a pressure inherent in a fluid in the well's annulus.

Each of the pressure-influenced bellows devices 6, 7 is hollow in form and contains an incompressible fluid, and the pressure-influenced bellows devices 6, 7 therefore must be designed as a closed unit. This may be achieved in several different ways, for example by one end of the pressure-influenced devices 6, 7 being connected to the support device 5, while their opposite end is delimited by an end surface (not shown).

The support device 5 according to FIG. 1 is in the form of a closed cylinder, where a through-going hole (not shown) is provided in the material of the closed cylinder's top and bottom surface. The first and second pressure-influenced bellow devices' 6, 7 open end (i.e. the end opposite the end surface) is then connected to this through-going hole, thereby forming a closed unit, consisting of the first pressure-influenced bellows device 6, the intermediate support device 5 and the second pressure-influenced bellows device 7.

A movable piston 13 is further mounted internally in the support device 5, where this piston 13 is permitted to be moved in the support device's 5 axial direction. The piston 13, moreover, may be designed in such a manner that together with the through-going hole in the support device's 5 top and/or bottom surface, it forms a metal-to-metal seal, with the result that when the piston 13 is brought into contact with the support device's 5 top or bottom surface, the first or the second pressure-influenced bellows device 6, 7 will not be permitted a further movement in its axial longitudinal direction. The device will be able to function without this movable piston internally in the support device.

In the support device 5 a delay device 14 may also be provided, where this delay device 14 is intended to delay the flow of the incompressible fluid in the support device 5. In its simplest form the delay device 14 comprises a plate provided with one or more through-going holes (not shown). The delay device 14 is mounted in a suitable manner in the support device 5. The device will be able to function without this delay device.

In FIG. 1 the first pressure-influenced bellows device 6 is connected to an activation mechanism 11, which is composed of a rack transmission or a slide valve.

By means of an external influence of the first and/or second pressure-influenced bellows device 6, 7, they will be able to be controlled so that the flap mechanism 9, which is connected to the second pressure-influenced bellows device 7, will be able to be pushed into the space 12, in order thereby to open up through-flow through the device, or out of the space 12, in order thereby to shut off through-flow through the device.

FIG. 2 illustrates a second embodiment of the device according to the present invention, where the external structure 1 is provided with a through-going bore 2, with the result that the external structure 1 is open at its ends. Internally in the bore 2, moreover, a stationary sleeve 3 is provided. The stationary sleeve 3 is connected in a suitable manner to the external structure 1. This results in the formation of an annulus, when viewed in a plane perpendicular to the external structure's 1 axial longitudinal direction, between the through-going bore 2 and the stationary sleeve 3. In this annulus a support device 5 is provided, where the support device 5 is securely connected to the external structure 1 and the stationary sleeve 3. Two pressure-influenced bellows devices, the first pressure-influenced bellows device 6 and the second pressure-influenced bellows device 7, are furthermore connected to the support device 5 via one end.

The design of the first and second pressure-influenced bellows devices 6, 7 corresponds to what has been described above (the version according to FIG. 1) and therefore no further explanation thereof will be given here.

The pressure-influenced bellows devices' 6, 7 one end surface 15 (i.e. the end surface opposite the connection to the support device 5) will therefore be subjected to an external influence, for example from a fluid located in the external structure's 1 through-going bore 2.

The second pressure-influenced bellows device 7 will furthermore be connected in a suitable manner to a unit which in this case is a movable sleeve 16, where this movable sleeve 16 will follow the second pressure-influenced bellows device's movement. The movable sleeve 16 will furthermore be arranged outside and partly overlapping the stationary sleeve 3, thereby forming a space between the stationary and the movable sleeves 3, 16. In this space is mounted a closing mechanism 9 (for example in the form of a damper) for the device, which closing mechanism 9 is permitted to rotate about its suspension point 17. This means that in an open position of the device (the closing mechanism's 9 retracted position), the closing mechanism 9 is “stored” in the space between the stationary and the movable sleeves 3, 16, thereby permitting a fluid to flow through the device, and in a closed position of the device (the closing mechanism's 9 extended position) it is brought into abutment with seat 18, in order thereby to close the device in a fluid-tight manner.

By means of an external influence of the first and/or second pressure-influenced bellows devices 6, 7, they will be able to be controlled in such a manner that the closing mechanism 9 will be able to be brought from an open to a closed position and vice versa, in order thereby to close or open the device.

FIG. 3 illustrates yet another embodiment of the device according to the present invention, where the closing mechanism is now composed of a ball valve 19. The ball valve 19 is provided with a through-going hole (only roughly illustrated), where the through-going hole will extend parallel to the external structure's longitudinal bore 2 in an open position of the device. When the pressure-influence bellows devices 6, 7 are influenced, on account of its connection with the second pressure-influenced bellows device 7, the ball valve 19 will be rotated 90 degrees relative to its open position, whereby the ball valve 19 will shut off a through-flow of fluid through the device. The pressure-influenced bellows devices' 6, 7 mode of operation will be as described for the other embodiments.

Only elements related to the invention have been explained and described in the above and a person skilled in the art will understand that the external structure may be designed as a unit or it may be composed of several elements which are interconnected. The device may furthermore have suitable devices for interconnection or mounting in a process fluid flow. A person skilled in the art will furthermore appreciate that several versions and modifications of the described and illustrated embodiments may be provided within the scope of the invention as defined in the attached claims. 

1. An actuator device, comprising a structure (1) having an internal through-going bore (2) and a pressure-influenced bellows comprising a first bellows (6) and a second bellows device (7) devices in fluid communication with each other, where the first (6) and second (7) bellows devices are arranged relative to the structure (1) in such a manner that during use they can experience different pressure influence, characterised in that the structure (1) comprises a through-going bore (2) and the pressure-influenced bellows (6, 7) are mounted at least partly in an annulus which at least partly is formed by the inner wall of the structure (1) and arranged around the through-going bore and where the second bellows device (7) is connected to a mechanical device (9) for activation of a unit.
 2. A device according to claim 1, characterised in that the unit is a valve device mounted in the through-going bore in the external structure for opening and closing of the through-going bore, and arranged in such a manner that this valve device can be activated between an open and a closed position by movement of the bellows as a consequence of pressure influence on the bellows.
 3. A device according to claim 1 or 2, characterised in that the bellows devices are mounted relatively outside the through-going bore in the external structure.
 4. A device according to claim 1 or 2, characterised in that the bellows devices are mounted at least partly internally in the through-going bore in the external structure.
 5. A device according to claim 4, characterised in that a sleeve is provided internally in the bore in the external structure, at a distance therefrom, thereby forming the annulus between them, where the annulus is closed at one end, where the sleeve, the structure and the bellows are configured in such a way that one of the bellows devices is mounted in a closed space formed within this annulus.
 6. A device according to claim 5, characterised in that both the first and the second bellows device are mounted in the annulus formed between the sleeve and the external structure.
 7. A device according to one of the above-mentioned claims, characterised in that the bellows forms an annular structure.
 8. A device according to one of the claims 1-6, characterised in that several bellows are provided along a circumference of the external structure.
 9. A device according to one of the above-mentioned claims, characterised in that the first and second bellows devices are in fluid connection with each other via a support device, which support device forms a transverse wall in the annulus.
 10. A device according to claim 1, characterised in that the first and second pressure-influenced bellows devices and the support device are filled with an incompressible fluid.
 11. A device according to claim 1, characterised in that the first and second pressure-influenced bellows devices are designed with the same shape and volume.
 12. A device according to claim 1, characterised in that the first and second pressure-influenced bellows devices are designed with the same shape, but with different volume.
 13. A device according to claim 1, characterised in that the first and second pressure-influenced bellows devices are designed with different shape and volume. 